Composite web and method of making the same



Aug. 8, 1933. H. A. CHASE ET AL 1,921,504

COMPOSITE WEB AND METHOD OF MAKING THE SAME Oniginal Filed April 27,1928 lizmzim Jmy & M6; i Z

li atented Aug. 8, 1933 UNET COMPOSTE WEB AND METHOD OF THE SAME HenryAlbert Chase and Harold Ray Titus,

Berlin, N. H.,

assignors to Brown (Company,

Berlin, N. H., a Corporation of Maine Application April 2'7, 1928,Serial No. 273,299 Renewed September 10, 1932 9 Claims.

This invention relates to a composite web which is adapted for a varietyof uses, such, for

instance, as filter sheet, medical gauze, or a foundation for variouscoated or impregnated products. It also relates to a continuous andeconomical method of making the same, using machinery of the papermakingtype.

According to the present invention, we produce a pulp web which isreinforced by fibrous material in the form of a comparatively open,knitted, or woven fabric, or in the form of yarns or threads, with orwithout lateral tying or filling strands, the term fabric as hereinafteremployed in the specification and claims, unless otherwise specified,being intended to mean fibrous material in any one of these forms. Thereinforcement of the web may be effected either by felting the pulpfibers on the fabric while it is continuously passing over and beingsupported on a moving foraminous backing such as Fourdrinier wire,'orelse by felting the pulp fibers on the backing and progressivelysuperimposing the fabric on the felting fibers and preferably con--tinuing felting on the fabric. The composite web is then dried by anysuitable method, the product comprising a pulp web reinforced eitherexteriorly or interiorly by the fabric, the pulp fibers being felted toand entangled in the fabric so that there is little inherent tendencyfor the pulp to separate therefrom.

The present invention may be applied to advantage when producing ahighly absorbent pulp web, the fibers of which exist in a substantiallyuncompacted but interfelted condition. Such a web may be produced on apaper machine if during the felting and drying of the web it does notundergo substantial compressing or compacting. As heretofore madewithout such fabric reinforcement, a web of this character is eminentlysuitable for uses where high absorbency is desired, but it possesses thedisadvantage of being difficult to handle without tearing. Thisdisadvantage renders the absorbent web unsuitable for use as a rawmaterial in a process which places it under stress, as it tends tobreak, even under comparatively low tensions. By reinforcing such a webin accordance with the present invention, it may even be drawn throughbaths of liquid saturant quite satisfactorily, the resulting productcontaining a maximum amount of saturant due to its highly absorptivecharacter. For instance, by passing the reinforced web through arubber-containing bath, e. g., a rubber-benzine solution, rubber latex,or an aqueous dispersion of rubber, a product having very high rubbercontent and possessing ex- .cellent characteristics for use as anartificial leather is produced. The reinforced web also lends itselfwell to coating or saturation with thermoplastic materials such asasphalt, or

waxes such as Montan and carnauba, with varnishes or lacquers of thenitrocellulose type, and with other materials.

The present invention will be specifically de-' scribed as applied inthe manufacture of, a highly absorbent web, the web being substantiallyuncompacted during the course of its manufacture, but it is to beunderstood that the web may, if desired, be more or less compacted,either while wet or after drying. With these and other features andobjects in view, the invention may be best understood from the followingmore detailed description thereof when considered in conjunction withthe accompanying drawing, wherein Figures 1 and 2 are diagrammatic andconventional views of one type of web-forming apparatus, respectivelyillustrating the methods of internally and externally reinforcing theweb.

Figure 3 represents a somewhat modified type of apparatus.

Figure 4 illustrates a method of forming a web with a plurality offabric reinforcements, using an apparatus similar to those shown inFigures 1 and 2.

Figures 5 and 6 are diagrammatic representations of the web-forming endof a paper machine of the Fourdrinier type, illustrating, respectively,methods of internally and externally reinforcing the web.

Figure '7 is an enlarged section through a reinforced web made inaccordance with the present invention, showing how the pulp fibersbecome entangled in the fabric.

Figures 8, 9, 10 and 11 are enlarged sections through various types ofreinforced webs which may be produced by the methods of our invention.

Referring in detail first to Figure 1 of the drawing,'1 indicates acylinder mould which rotates in a pulp suspension maintained in a vat 2,a moving Fourdrinier wire 3 being guided into contact with theunsubmerged portion of the roll and passing around the submerged portionof the mould. The pulp suspension delivered into the vat is pref erablyof very dilute consistency, containing, say, 005% to 01% fiber,preferably in an unbeaten condition, especially when a highly absorbentweb is desired. A fabric, preferably of an open weave, such ascheesecloth, is shown being unwound from a roll 4 and passing into thepulp suspension and into contact with the wire 3 about the mould at apoint somewhat removed from the surface of the pulp suspension. As thewire passes into the pulp suspension and around the mould, a layer ofpulp fibers is deposited thereon. As soon as the fabric comes intocontact with the wet pulp layer, pulp fibers deposit on the fabric asthe water continues to pass into the cylinder mould from which it isremoved, so that the fabric lies between two pulp layers the fibers ofwhich are entangled therewith. The wire moves out of the pulpsuspension, carrying a wet pulp web reinforced interiorly with a fabriclayer as shown in Figure 8. This entangling of the fibers with thefabric is illustrated in Figures '7 and 8, the fabric first having beenbrought into contact with wet pulp the fibers of which have penetratedthereinto, whereupon felting of other fibers has been produced directlyon the opposite face of the fabric fibers penetrating the fabric fromthat face. To obtain a product of maximum absorbency, the web should bedewatered without a substantial compacting of its fibers.

As shown in Figure 1, this may be accomplished by passing the wire withthe wet web thereon around one or more drum dryers 5, the dry webproduced being removed from the wire and reeled, and the wire returningto the cylinder mould. If the web is to be reinforced exteriorly, thefabric may be passed into contact with the unsubmerged portion of thecylinder mould, as shown in Figure 2, the pulp fibers being felted onthe outer face of the fabric and penetrating the fabric from that face,resulting in a product a section of which is illustrated in Figure 9.

Instead of completely drying the web while on the wire, it may bepartially dried while on the wire and then dried to completion afterremoval therefrom. Such a procedure is illustrated in Figure 3, the webbeing on the wire while passing over a suction box 6, and over a heatingdevice 7, and then being transferred from the wire and passed around adrum dryer, the wire returning over a guide roll 8 to the cylindermould.

A web having a plurality of fabric layers spaced apart may also beformed by the method of our invention. This may be done, as shown inFigure 4, by passing a plurality of webs of fabric to the cylinder mouldat different levels of submergence, pulp being deposited on each of thefabric layers before the succeeding fabric layer is applied. This methodresults in a product shown in section in Figure 10, a plurality ofspaced layers of fabric 1 being embedded in the pulp web, the fibers ofwhich are more or less entangled in the fabric layers.

Reinforced webs such as hereinbefore described may be produced on papermachines of the Fourdrinier type, by passing the fabric superposed onthe Fourdrinier wire and running the pulp out on the fabric to produce aweb reinforced exteriorly, or running the pulp out on the wire above andbelow the fabric, so as to embed the fabric in the pulp. Thefirst-mentioned method is illustrated in Figure 5, the fabric beingunwound from a roll and fed through a supply of pulp suspensionmaintained in a fiow box 9. The fabric is drawn through the pulpsuspension by a pair of rolls 10 at the same rate of speed as the rateof travel of a Fourdrinier wire 11 onto which the fabric and pulpdischarges through a transverse opening 13 in the box, and

over an apron 14 extending from the lower edge overlying the wire, andthe pulp overlying the fabric. The pulp which passes through the openingthen felts or deposits on the fabric to produce a web reinforcedexteriorly with fabric, as illustrated in Figure 9. According to thesecond method, the fabric is guided midway of the opening 13, so as todivide the pulp flowing through the opening, one portion of the streampassing under the fabric and felting on the wire, and the other portionpassing above the fabric and felting on the fabric. This produces a webreinforced by the fabric between its faces, as illustrated in Figure 8.The wet web may be either partially or completely dried on theFourdrinier wire, as already described. Where the fabric is woven, as inthe case of cheesecloth, webs which are reinforced transversely andlongitudinally are produced. All that may be necessary in some cases,however, is to reinforce the web lengitudinally, so that it may be drawnor subjected to longitudinal tension only without breaking.

When this is the case, the web may be reinforced by using strandmaterial such as yarns or threads in place of fabric such ascheesecloth, the strands being arranged in generally parallelrelationship while felting of the pulp fibers is being effected. Thisresults in a product such as illustrated in section in Figure 11, thestrands of fibrous material being embedded in the web and reinforcing itlongitudinally, or of course the strands may be positioned at one faceonly of the web, in a manner similar to the woven fabric reinforcementsshown in Figures 7 and 9.

While fiber of any suitable origin, for instance, sulphite or kraftpulp, may be'employed as a raw material in the production of the web ofthe present invention, if a high grade absorbent product suitable foruse as filter sheet or medical gauze is desired, we preferably usecotton or rag fiber or wood fiber which has been refined to high alphacellulose content. If the product is to be coated or saturated withrubber or with other materials, it'may be preferable to employ fibers ofcomparatively high average fiberlength, such as jute, hemp, and manila,owing to the particular physical characteristics which such fibersimpart to the product.

Having thus described certain embodiments of this invention, it isevident to those skilled in the art that various changes andmodifications might be made therein without departing from the spirit orscope of invention as defined in the appended claims.

What we claim is:

1. A method of making an absorbent reinforced pulp web, which comprisespassing a fabric of the nature of cheesecloth over a moving foraminousbacking, felting pulp fibers on and into the fabric, and drying theresulting web while maintained in substantially uncompacted condition,thereby keeping the felted bond between the pulp fibers and fabricundisturbed.

2. A method of making an absorbent reinforced pulp web, which comprisespassing a fabric of the nature of cheesecloth over a moving Fourdrinierwire, felting pulp fibers on and into the fabric, and drying theresulting web in substantially uncompressed condition while it issupported by the wire, thereby keeping the felted bond between the pulpfibers and fabric undisturbed.

3. A method of making a reinforced pulp web, which comprises felting-thefiber on a foraminous moving backing, progressively superimposing afabric of the nature of cheesecloth on the felting face of the pulpsuspension and after a layer of pulp has been deposited on said wire,passing a porous fabric of the nature of cheesecloth about said mouldinto contact with said pulp layer to cause pulp to deposit on and topenetrate into the fabric as water continues to pass into the cylindermould; and drying the composite web in substantially uncompressedcondition, therebypreserving unimpaired the union between the pulp andfabric.

5. A method of making a reinforced pulp web, which comprises maintaininga vat of aqueous pulp suspension in which rotates a cylinder mould intowhich water of the pulp suspension may pass; passing about said mould aFourdrinier wire on which pulp may deposit While water is passing intothe mould; at a point below the surface of the pulp suspension and aftera layer of pulp has been deposited on said wire passing a porous fabricof the nature of cheesecloth about said mould into contact with saidpulp layer to produce a wet pulp web felted to, and reinforcedinteriorly with, a fabric layer; and dewatering and drying thereinforced web in substantially pulp suspension in which rotates acylinder mould; passing about said mould a Fourdrinier wire on whichpulp may deposit; at different levels of submergence passing porous websof fabric of the nature of cheesecloth about the cylinder mould toeffect a deposition of pulp on, and felting of pulp to, each of thefabric webs before the succeeding fabric web is applied; and drying thecomposite web while maintained in substatnially uncompacted condition,thereby keeping the felted bond between the pulp fibers and fabricundisturbed.

'7. An article of manufacture consisting of a web of pulp reinforced byan open, loosely woven textile fabric of the nature of cheesecloth, thepulp fibers having been deposited and felted on and into the fabric fromaqueous suspension and having been dried while maintained insubstantially the same uncompacted condition and bonded relation withthe fabric as deposited from aqueous suspension.

8. An article of manufacture consisting of a web of substantiallyunbeaten wood pulp reinforced by an open, loosely woven textile fabricof the nature of cheesecloth, the pulp fibers having been deposited andfelted on and into the fabric from aqueous suspension and having beendried while maintained in substantially the same uncompacted conditionand bonded relation with the fabric as deposited from aqueoussuspension.

9. An article of manufacture consisting of a web of substantiallyunbeaten wood pulp refined to high alpha cellulose content andreinforced by an open, loosely woven textile fabric of the nature ofcheesecloth, the pulp fibers having been deposited and felted on andinto the fabric from aqueous suspension and having been dried whilemaintained in substantially the same uncompacted condition and bondedrelation with the fabric as deposited from aqueous suspension.

HENRY ALBERT CHASE. HAROLD RAY TITUS.

